Why not recommend Italian coffee beans instead of grinding powder? How long is the shelf life of coffee powder?

Basically, shops that sell coffee beans have a surrogate grinding service, but if you use it to extract espresso, Qianjie does not recommend it.

There are two main reasons, one of which is the problem that it is easy to "stale". This is a common problem with all pre-ground coffee powder, but it is especially serious when used in espresso.

In addition to the accelerated loss of flavor, the loss of carbon dioxide in the beans will also accelerate, and the Crema of espresso is made up of carbon dioxide and oil, so making espresso from pre-ground coffee powder only has a rich amount of oil in the first few days, followed by a decrease in Crema visible to the naked eye every day.

The second reason is that espresso has a very high grinding accuracy. For example, the coffee machine is different, the corresponding degree of grinding may have a more obvious deviation. The coffee shop calibrated the grinding degree of espresso powder is set for the coffee machine used by the shop. Because of the large boiler, the commercial coffee machine in the coffee shop will be more stable under pressure. And some household machines will say in the manual that there can be more than a dozen bar pressure, but this pressure is unstable, there may be enough pressure in the first few seconds, but then the pressure begins to drop, which is reflected in the slow and long time of coffee extraction.

Even if you buy the same coffee maker in the coffee shop, you can solve the problem of the coffee machine. Then we are faced with the problem of the state of coffee beans.

In Italian extraction, the basic coffee shop adjusts the concentration parameters before opening every morning, and most of the objects are the scale of the bean grinder. Because coffee beans emit gas every day, yesterday's parameters may not be able to extract today's beans perfectly, so you need to confirm the concentrated state every day and adjust in time when something goes wrong. To give two examples, the first example is that yesterday's extraction parameters were 20g powder extraction 40g liquid, time 26 seconds, today using yesterday's parameters to extract coffee, the same scale, 20g powder extraction 40g liquid, time 22 seconds, then you need to adjust the grinding degree.

The second example is that yesterday's extraction parameters are 20g powder extraction 40g liquid, time 26 seconds, today using yesterday's parameters to extract coffee, the same scale, 20g powder extraction 40g liquid, time 26 seconds, but today's flavor is different from yesterday's flavor, there is an unpleasant taste, also need to adjust the grinding degree.

The adjustment range for the degree of grinding is actually very small, basically each adjustment is controlled within 0.5 grid. This 0.5 grid difference, if observed by the naked eye and touched by the hand, can not be distinguished at all, but put on the coffee machine to extract coffee, the difference appears, 0.5 grid extraction time difference of 7 seconds.

Therefore, if there is a pursuit of coffee oil and coffee flavor, Qianjie is not recommended to buy espresso powder or substitute grinding powder directly.